nuxt-vitest#

A vitest environment for testing code that needs a Nuxt runtime environment

Warning This library is in active development and you should pin the patch version before using.

Installation#

First install nuxt-vitest:

pnpm add -D nuxt-vitest

# or
yarn add --dev nuxt-vitest
npm i -D nuxt-vitest

Add nuxt-vitest to your nuxt.config.js:

export default defineNuxtConfig({
  // ...
  modules: [
    'nuxt-vitest'
  ]
})

Then create a vitest.config.mjs with the following content:

import { defineVitestConfig } from 'nuxt-vitest/config'

export default defineVitestConfig({
  // any custom vitest config you require
})

Setting environment for your tests

By default, nuxt-vitest will not change your default Vitest environment, so you can do fine-grain opt-in and run Nuxt tests together with other unit tests.

We provided a filename convention that test files contains .nuxt., like *.nuxt.test.{js,ts} and *.nuxt.spec.{js,ts}, will be run in Nuxt environment automatically.

Or you can add @vitest-environment nuxt in your test file as a comment to opt-in per test file.

// @vitest-environment nuxt
import { test } from 'vitest'

test('my test', () => {
  // ... test with Nuxt environment!
})

Finally, you can set environment: 'nuxt', to enable Nuxt environment for all tests.

// vitest.config.ts
import { fileURLToPath } from 'node:url'
import { defineVitestConfig } from 'nuxt-vitest/config'

export default defineVitestConfig({
  test: {
    environment: 'nuxt',
    // you can optionally set nuxt-specific environment options
    // environmentOptions: {
    //   nuxt: {
    //     rootDir: fileURLToPath(new URL('./playground', import.meta.url)),
    //     overrides: {
    //       // other nuxt config you want to pass
    //     }
    //   }
    // }
  }
})

If you have set environment: 'nuxt' by default, you can then opt-out of the default environment per test file as needed.

// @vitest-environment node
import { test } from 'vitest'

test('my test', () => {
  // ... test without Nuxt environment!
})

👉 Important notes#

When you run your tests within the Nuxt environment, they will be running in a happy-dom environment. Before your tests run, a global Nuxt app will be initialised (including, for example, running any plugins or code you've defined in your app.vue).

This means you should be take particular care not to mutate the global state in your tests (or, if you have, to reset it afterwards).

🛠️ Helpers#

nuxt-vitest provides a number of helpers to make testing Nuxt apps easier.

`mountSuspended`#

// TODO:

`mockNuxtImport`#

mockNuxtImport allows you to mock Nuxt's auto import functionality. For example, to mock useStorage, you can do so like this:

import { mockNuxtImport } from 'nuxt-vitest/utils'

mockNuxtImport('useStorage', () => {
  return () => {
    return { value: 'mocked storage' }
  }
})

// your tests here

Note: mockNuxtImport can only be used once per test file. It is actually a macro that gets transformed to vi.mock and vi.mock is hoisted, as described here.

If you need to mock a Nuxt import and provide different implementations between tests, you can do it by using a global variable as the returned value of your mock function and change its implementation within each test. Be careful to restore mocks before or after each test to undo mock state changes between runs.

// useStorageMock.ts
let useStorageMock = vi.fn(() => {
  return { value: 'mocked storage' }
})
export default useStorageMock

import useStorageMock from './useStorageMock'
import { mockNuxtImport } from 'nuxt-vitest/utils'

mockNuxtImport('useStorage', () => {
  return () => useStorageMock()
})

// Then, inside a test
useStorageMock.mockImplementation(() => {
  return { value: 'something else' }
})

`mockComponent`#

mockComponent allows you to mock Nuxt's component. The first argument can be the component name in PascalCase, or the relative path of the component. The second argument can is a factory function that returns the mocked component.

For example, to mock MyComponent, you can:

import { mockComponent } from 'nuxt-vitest/utils'

mockComponent('MyComponent', {
  props: {
    value: String
  },
  setup(props) {
    // ...
  }
})

// relative path or alias also works
mockComponent('~/components/my-component.vue', async () => {
  // or a factory function
  return {
    setup(props) {
      // ...
    }
  }
})

// or you can use SFC for redirecting to a mock component
mockComponent('MyComponent', () => import('./MockComponent.vue'))

// your tests here

Note: You can't reference to local variables in the factory function since they are hoisted. If you need to access Vue APIs or other variables, you need to import them in your factory function.

mockComponent('MyComponent', async () => {
  const { ref, h } = await import('vue')

  return {
    setup(props) {
      const counter = ref(0)
      return () => h('div', null, counter.value)
    }
  }
})

Conflict with @nuxt/test-utils#

nuxt-vitest and @nuxt/test-utils need to run in different testing environments and so can't be used in the same file.

If you would like to use @nuxt/test-utils to conduct end-to-end tests on your Nuxt app, you can split your tests into separate files. You then either specify a test environment per-file with the special // @vitest-environment nuxt comment, or name your nuxt-vitest files with the .nuxt.spec.ts extension.

app.nuxt.spec.js

import { mockNuxtImport } from "nuxt-vitest/utils";

mockNuxtImport('useStorage', () => {
  return () => {
    return { value: 'mocked storage' }
  }
})

app.e2e.spec.js

import { setup, $fetch } from '@nuxt/test-utils';

await setup({
  setupTimeout: 10000,
});

// ...

💻 Development#

Clone this repository
Enable Corepack using corepack enable (use npm i -g corepack for Node.js < 16.10)
Install dependencies using pnpm install
Stub the library using pnpm dev:prepare
Run interactive tests using pnpm test

License#

Made with ❤️

Published under the MIT License.

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